To a suspension of 341 parts of aluminum chloride in 1740 parts of carbon
disulfide are added 96 parts of fluorobenzene with stirring and cooling. While
the temperature is maintained at about 10°C, 141 parts of γ-chlorobutyryl
chloride are added. After the addition is completed, the cooling bath is
removed and the stirring is continued for 2 hours. The reaction mixture is
poured into ice water. The organic layer is separated, washed with water, dried
over anhydrous sodium sulfate, and filtered. The filtrate is concentrated under
reduced pressure, and the residue is distilled to yield γ-chloro-p-fluorobutyrophenone
boiling at about 136°-142°C/6 mm
A mixture of 6.6 parts of γ-chloro-p-fluoro-butyrophenone and 12.5 parts of 1-
(o-anisyl)piperazine is heated for 10 hours at a temperature of 110°C. The
reaction mixture is treated with 800 parts of ether and filtered. The ether
layer is washed with water, dried over anhydrous potassium carbonate and
filtered, whereupon hydrogen chloride gas is introduced into the solution. The
precipitate is collected on a filter and dissolved in a mixture of 240 parts of 2-
propanol and 80 parts of acetone to yield 1-[γ-(p-fluorobenzoyl)propyl]-4-(o-anisyl)piperazine hydrochloride. This monohydrochloride is collected on a filter
and dissolved in 240 parts of 2-propanol. Anhydrous, gaseous hydrogen
chloride is passed through the solution. On cooling, the 1-[γ-(p-fluorobenzoyl)
propyl]-4-(o-anisyl)piperazine dihydrochloride precipitates.
A second crop of product is obtained by passing hydrogen chloride gas
through the solution of mother liquors. The pale-brown, amorphous powder is
collected on a filter and found to melt at about 205°-205.5°C.
This salt is dissolved in water and treated with sodium hydroxide. The
precipitated base is recovered by filtration and recrystallized from diisopropyl
ether. The white crystals melt at about 67.5°-68.5°C.
